Antimicrobial resistance (AMR) is a major ongoing global health challenge, in which bacteria develop the ability to resist antimicrobial agents designed to eliminate them. The societal costs associated with AMR include both substantial economic burden and loss of human life, as AMR is increasingly responsible for, and contributory to, mortality worldwide. AMR is further exacerbated by bacterial biofilm formation, which promotes tolerance to antimicrobial treatments. Therefore, identifying effective antimicrobial strategies to reduce biofilm formation on surfaces has become crucial to counteract AMR. Layered Double Hydroxides (LDHs) are metal-based, brucite-like nanomaterials composed of bivalent and trivalent metal cations with intercalated anions. LDH thin-film coatings exhibit physicochemical properties that can potentially reduce bacterial colonisation of surfaces and consequently inhibit biofilm initiation. The aim of this study is to investigate the antimicrobial performance of LDHs as intrinsic antimicrobial surfaces, exploring the influence of chemical composition, nanotopography, and wettability on biofilm formation against Escherichia Coli, Staphylococcus Aureus, and Pseudomonas Aeruginosa, selected for their relevance in antimicrobial research. Four aluminium-based LDH formulations (ZnAl-NO3, ZnAl-Cl2, MgAl-NO3, MgAl-Cl2) were synthesised either via coprecipitation or in situ growth on aluminium substrates and characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and contact angle measurements to assess crystalline structure, morphology, chemical composition, and surface wettability. The antimicrobial performance of each formulation and synthesis route was evaluated by exposing bacterial strains to the LDH surfaces and quantifying colony-forming units (CFU mL-1). ZnAl-LDH surfaces exhibited significant antimicrobial activity against E. Coli and S. Aureus, with a marked reduction in CFU mL-1 compared to controls. In contrast, MgAl-LDH surfaces showed no significant antimicrobial effect and, in some cases, a slight increase in CFU mL⁻¹. No reduction in bacterial growth was observed for P. Aeruginosa across all formulations and surface types. The enhanced antimicrobial performance of ZnAl-LDH is attributed to the combined effects of zinc-based chemical composition, surface wettability, and sharp platelet-like nanotopographical features that may compromise bacterial cell membranes. Overall, these findings demonstrate the synergistic role of chemical composition, nanotopography, and wettability in modulating bacterial colonisation and biofilm formation, highlighting ZnAl-LDH nanostructured coatings as promising antimicrobial surfaces for relevant biomedical applications.
Delle Fave, F., Froio, M., Cisternino, D., Jayaraman, S., Ashley, C., Medaglia, P.g., et al. (2026). Characterising the antimicrobial performance of engineered layered double hydroxide surfaces for biofilm control. SURFACES AND INTERFACES.
Characterising the antimicrobial performance of engineered layered double hydroxide surfaces for biofilm control
Delle Fave F.;Froio M.;Cisternino D;Medaglia P. G.;
2026-01-01
Abstract
Antimicrobial resistance (AMR) is a major ongoing global health challenge, in which bacteria develop the ability to resist antimicrobial agents designed to eliminate them. The societal costs associated with AMR include both substantial economic burden and loss of human life, as AMR is increasingly responsible for, and contributory to, mortality worldwide. AMR is further exacerbated by bacterial biofilm formation, which promotes tolerance to antimicrobial treatments. Therefore, identifying effective antimicrobial strategies to reduce biofilm formation on surfaces has become crucial to counteract AMR. Layered Double Hydroxides (LDHs) are metal-based, brucite-like nanomaterials composed of bivalent and trivalent metal cations with intercalated anions. LDH thin-film coatings exhibit physicochemical properties that can potentially reduce bacterial colonisation of surfaces and consequently inhibit biofilm initiation. The aim of this study is to investigate the antimicrobial performance of LDHs as intrinsic antimicrobial surfaces, exploring the influence of chemical composition, nanotopography, and wettability on biofilm formation against Escherichia Coli, Staphylococcus Aureus, and Pseudomonas Aeruginosa, selected for their relevance in antimicrobial research. Four aluminium-based LDH formulations (ZnAl-NO3, ZnAl-Cl2, MgAl-NO3, MgAl-Cl2) were synthesised either via coprecipitation or in situ growth on aluminium substrates and characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and contact angle measurements to assess crystalline structure, morphology, chemical composition, and surface wettability. The antimicrobial performance of each formulation and synthesis route was evaluated by exposing bacterial strains to the LDH surfaces and quantifying colony-forming units (CFU mL-1). ZnAl-LDH surfaces exhibited significant antimicrobial activity against E. Coli and S. Aureus, with a marked reduction in CFU mL-1 compared to controls. In contrast, MgAl-LDH surfaces showed no significant antimicrobial effect and, in some cases, a slight increase in CFU mL⁻¹. No reduction in bacterial growth was observed for P. Aeruginosa across all formulations and surface types. The enhanced antimicrobial performance of ZnAl-LDH is attributed to the combined effects of zinc-based chemical composition, surface wettability, and sharp platelet-like nanotopographical features that may compromise bacterial cell membranes. Overall, these findings demonstrate the synergistic role of chemical composition, nanotopography, and wettability in modulating bacterial colonisation and biofilm formation, highlighting ZnAl-LDH nanostructured coatings as promising antimicrobial surfaces for relevant biomedical applications.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
